It is known that performing many surgery operations entails the presence of an extracorporeal blood circuit in which various devices, and typically an oxygenation apparatus, are inserted.
During the operation, the conditions of the blood at the inlet and outlet of these devices, i.e. of the blood which operators usually call venous and arterial blood respectively, are checked; for this purpose, devices which allow to separately draw venous and arterial blood, according to the requirements, are commercially available. These devices furthermore, allow performance of another action which is often necessary during said operation, i.e. the injection of drugs into the blood.
Many known devices essentially comprise a coupling for a syringe intended to draw samples of blood and another coupling for a syringe intended to inject drugs, such couplings may be connected by three-way cocks arranged in series; although they are widespread, these devices are not devoid from some disadvantageous drawbacks.
First of all, a certain difficulty in operating with a plurality of three-way cocks is determined by observation of the required functional conditions in these devices, and the possibility of actuation errors. Escape of blood therefrom is a particular difficulty.
A device for selectively sampling from two sections of a line comprising a selection element with a cavity for use with a syringe is described in U.S. Pat. No. 4,736,636.